Passive performance of glazed components in heating and cooling of an open-space office under controlled indoor thermal comfort

Publication date: February 2014
Source:Building and Environment, Volume 72
Author(s): Francesca Cappelletti , Alessandro Prada , Piercarlo Romagnoni , Andrea Gasparella
According to the Fanger's comfort theory, the individual thermal sensation is mainly connected with the thermal balance of the human body. This balance and the related comfort indicators (the Predicted Mean Vote, PMV, and the correlated Predicted Percentage of Dissatisfied, PPD) depend on four environmental parameters (air temperature, humidity and velocity, and internal envelope mean radiant temperature) and two variables connected with the human being (physical activity and clothing). Differently from the other environmental parameters under the system control, the mean radiant temperature is strongly conditioned by the envelope characteristics, and in particular, by the presence of glazed surfaces whose insulating performance is commonly lower than the one of opaque components. Transparent components also admit solar radiation into the indoor environment, affecting the thermal balance of the building and of the occupants. In this paper, the heating and cooling energy needs of an open-space office with different windows' characteristics have been analyzed under controlled internal comfort conditions. A set of configurations given by different windows' glazing systems, area, disposition and orientation has been simulated, considering the climatic conditions of Paris, Milan and Rome. The passive energy performance of the different glazing solutions has then been compared accounting for the long-term comfort conditions (on seasonal basis). The time distribution of the Predicted Mean Vote (PMV) and the Discomfort Time weighted by the Predicted Percent of Dissatisfied (WDT PPD ) are analyzed, including also the effect of the diffuse and beam solar radiation directly reaching the occupants through the windows.

Graphical abstract